If your SSL CERTIFICATE  was not auto installed after host account purchase. Kindlly log into your cpanel, cpanel can be found on the welcome email you received.

Once you have cpanel login , login cpanel then search SSL from cpanel search bar, or you can scroll down  to security under it you will see SSL/TLS STATUS click on it after enter your website name on the ssl search space , It will highlight your domain , and sub-domain, finally click on RUN AUTO SSL wait for some minutes once it is done SSL will be installed on your new domain.